diff mbox series

[v1,2/2] s390/kvm: Move bitfields for dat tables

Message ID 20240703155900.103783-3-imbrenda@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series s390: Two small fixes and improvements | expand

Commit Message

Claudio Imbrenda July 3, 2024, 3:59 p.m. UTC 
Move and improve the struct definitions for DAT tables from gaccess.c
to a new header.

Once in a separate header, the structs become available everywhere. One
possible usecase is to merge them in the s390 pte_t and p?d_t
definitions, which is left as an exercise for the reader.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 arch/s390/include/asm/dat-bits.h | 170 +++++++++++++++++++++++++++++++
 arch/s390/kvm/gaccess.c          | 163 +----------------------------
 2 files changed, 173 insertions(+), 160 deletions(-)
 create mode 100644 arch/s390/include/asm/dat-bits.h

Comments

Nico Boehr July 9, 2024, 8:45 a.m. UTC | #1 
Quoting Claudio Imbrenda (2024-07-03 17:59:00)
> Move and improve the struct definitions for DAT tables from gaccess.c
> to a new header.
> 
> Once in a separate header, the structs become available everywhere. One
> possible usecase is to merge them in the s390 pte_t and p?d_t
> definitions, which is left as an exercise for the reader.
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
Alexander Gordeev July 11, 2024, 3:16 p.m. UTC | #2 
On Wed, Jul 03, 2024 at 05:59:00PM +0200, Claudio Imbrenda wrote:

Hi Claudio,

> Once in a separate header, the structs become available everywhere. One
> possible usecase is to merge them in the s390 
> definitions, which is left as an exercise for the reader.

Is my understanding correct that you potentially see page_table_entry::val /
region?_table_entry.*::val / segment_table_entry.* merged with pte_t::pte /
p?d_t::p?d?

Thanks!
Claudio Imbrenda July 11, 2024, 4:23 p.m. UTC | #3 
On Thu, 11 Jul 2024 17:16:23 +0200
Alexander Gordeev <agordeev@linux.ibm.com> wrote:

> On Wed, Jul 03, 2024 at 05:59:00PM +0200, Claudio Imbrenda wrote:
> 
> Hi Claudio,
> 
> > Once in a separate header, the structs become available everywhere. One
> > possible usecase is to merge them in the s390 
> > definitions, which is left as an exercise for the reader.  
> 
> Is my understanding correct that you potentially see page_table_entry::val /
> region?_table_entry.*::val / segment_table_entry.* merged with pte_t::pte /
> p?d_t::p?d?
> 
> Thanks!

that depends on how you want to do the merge

you could do:

typedef union {
	unsigned long pte;
	union page_table_entry hw;
	union page_table_entry_softbits sw;
} pte_t;

then you would have pte_t::pte and pte_t::hw::val; unfortunately it's
not possible to anonymously merge a named type.. 

this would be great but can't be done*:

typedef union {
	unsigned long pte;
	union page_table_entry;
} pte_t;

[*] gcc actually supports it with an additional feature switch, but
it's not standard C and I seriously doubt we should even think about
doing it

another possibility is a plain

typedef union page_table_entry pte_t;

and then fix pte_val() and similar, but then you won't have the
softbits.


in the end, it's up to you how you want to merge them. I will
have my own unions that I will use only inside KVM, that's enough for
me.
Heiko Carstens July 12, 2024, 9:56 a.m. UTC | #4 
On Thu, Jul 11, 2024 at 06:23:48PM +0200, Claudio Imbrenda wrote:
> On Thu, 11 Jul 2024 17:16:23 +0200
> Alexander Gordeev <agordeev@linux.ibm.com> wrote:
> > Hi Claudio,
> > 
> > > Once in a separate header, the structs become available everywhere. One
> > > possible usecase is to merge them in the s390 
> > > definitions, which is left as an exercise for the reader.  
> > 
> > Is my understanding correct that you potentially see page_table_entry::val /
> > region?_table_entry.*::val / segment_table_entry.* merged with pte_t::pte /
> > p?d_t::p?d?
> 
> that depends on how you want to do the merge
> 
> you could do:
> 
> typedef union {
> 	unsigned long pte;
> 	union page_table_entry hw;
> 	union page_table_entry_softbits sw;
> } pte_t;
> 
> then you would have pte_t::pte and pte_t::hw::val; unfortunately it's
> not possible to anonymously merge a named type.. 
> 
> this would be great but can't be done*:
> 
> typedef union {
> 	unsigned long pte;
> 	union page_table_entry;
> } pte_t;
> 
> [*] gcc actually supports it with an additional feature switch, but
> it's not standard C and I seriously doubt we should even think about
> doing it
> 
> another possibility is a plain
> 
> typedef union page_table_entry pte_t;
> 
> and then fix pte_val() and similar, but then you won't have the
> softbits.
> 
> 
> in the end, it's up to you how you want to merge them. I will
> have my own unions that I will use only inside KVM, that's enough for
> me.

We discussed this, and I really don't think we want this for the software
defined bits. In general I do like the idea of having bit fields and let
gcc do the decoding. But we have so many masks we use every for ptes and
friends that a single assignment won't work in most cases. So we eiter have
to do several assignments (which sometimes is a no-go when block concurrent
updates are required), or we have to stay with using both the existing
defines plus the new unions - which makes things even more complicated.

There might be uses cases where the hardware structures are also useful for
s390 core code, but I don't think we should go the route outlined above.
diff mbox series

Patch

diff --git a/arch/s390/include/asm/dat-bits.h b/arch/s390/include/asm/dat-bits.h
new file mode 100644
index 000000000000..d8afd13be48c
--- /dev/null
+++ b/arch/s390/include/asm/dat-bits.h
@@ -0,0 +1,170 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * DAT table and related structures
+ *
+ * Copyright IBM Corp. 2024
+ *
+ */
+
+#ifndef _S390_DAT_BITS_H
+#define _S390_DAT_BITS_H
+
+union asce {
+	unsigned long val;
+	struct {
+		 unsigned long rsto: 52;/* Region- or Segment-Table Origin */
+		 unsigned long     : 2;
+		 unsigned long g   : 1; /* Subspace Group control */
+		 unsigned long p   : 1; /* Private Space control */
+		 unsigned long s   : 1; /* Storage-Alteration-Event control */
+		 unsigned long x   : 1; /* Space-Switch-Event control */
+		 unsigned long r   : 1; /* Real-Space control */
+		 unsigned long     : 1;
+		 unsigned long dt  : 2; /* Designation-Type control */
+		 unsigned long tl  : 2; /* Region- or Segment-Table Length */
+	};
+};
+
+enum {
+	ASCE_TYPE_SEGMENT = 0,
+	ASCE_TYPE_REGION3 = 1,
+	ASCE_TYPE_REGION2 = 2,
+	ASCE_TYPE_REGION1 = 3
+};
+
+union region1_table_entry {
+	unsigned long val;
+	struct {
+		unsigned long rto: 52;/* Region-Table Origin */
+		unsigned long    : 2;
+		unsigned long p  : 1; /* DAT-Protection Bit */
+		unsigned long    : 1;
+		unsigned long tf : 2; /* Region-Second-Table Offset */
+		unsigned long i  : 1; /* Region-Invalid Bit */
+		unsigned long    : 1;
+		unsigned long tt : 2; /* Table-Type Bits */
+		unsigned long tl : 2; /* Region-Second-Table Length */
+	};
+};
+
+union region2_table_entry {
+	unsigned long val;
+	struct {
+		unsigned long rto: 52;/* Region-Table Origin */
+		unsigned long    : 2;
+		unsigned long p  : 1; /* DAT-Protection Bit */
+		unsigned long    : 1;
+		unsigned long tf : 2; /* Region-Third-Table Offset */
+		unsigned long i  : 1; /* Region-Invalid Bit */
+		unsigned long    : 1;
+		unsigned long tt : 2; /* Table-Type Bits */
+		unsigned long tl : 2; /* Region-Third-Table Length */
+	};
+};
+
+struct region3_table_entry_fc0 {
+	unsigned long sto: 52;/* Segment-Table Origin */
+	unsigned long    : 1;
+	unsigned long fc : 1; /* Format-Control */
+	unsigned long p  : 1; /* DAT-Protection Bit */
+	unsigned long    : 1;
+	unsigned long tf : 2; /* Segment-Table Offset */
+	unsigned long i  : 1; /* Region-Invalid Bit */
+	unsigned long cr : 1; /* Common-Region Bit */
+	unsigned long tt : 2; /* Table-Type Bits */
+	unsigned long tl : 2; /* Segment-Table Length */
+};
+
+struct region3_table_entry_fc1 {
+	unsigned long rfaa: 33;/* Region-Frame Absolute Address */
+	unsigned long     : 14;
+	unsigned long av  : 1; /* ACCF-Validity Control */
+	unsigned long acc : 4; /* Access-Control Bits */
+	unsigned long f   : 1; /* Fetch-Protection Bit */
+	unsigned long fc  : 1; /* Format-Control */
+	unsigned long p   : 1; /* DAT-Protection Bit */
+	unsigned long iep : 1; /* Instruction-Execution-Protection */
+	unsigned long     : 2;
+	unsigned long i   : 1; /* Region-Invalid Bit */
+	unsigned long cr  : 1; /* Common-Region Bit */
+	unsigned long tt  : 2; /* Table-Type Bits */
+	unsigned long     : 2;
+};
+
+union region3_table_entry {
+	unsigned long val;
+	struct region3_table_entry_fc0 fc0;
+	struct region3_table_entry_fc1 fc1;
+	struct {
+		unsigned long   : 53;
+		unsigned long fc: 1; /* Format-Control */
+		unsigned long   : 4;
+		unsigned long i : 1; /* Region-Invalid Bit */
+		unsigned long cr: 1; /* Common-Region Bit */
+		unsigned long tt: 2; /* Table-Type Bits */
+		unsigned long   : 2;
+	};
+};
+
+struct segment_table_entry_fc0 {
+	unsigned long pto: 53;/* Page-Table Origin */
+	unsigned long fc : 1; /* Format-Control */
+	unsigned long p  : 1; /* DAT-Protection Bit */
+	unsigned long    : 3;
+	unsigned long i  : 1; /* Segment-Invalid Bit */
+	unsigned long cs : 1; /* Common-Segment Bit */
+	unsigned long tt : 2; /* Table-Type Bits */
+	unsigned long    : 2;
+};
+
+struct segment_table_entry_fc1 {
+	unsigned long sfaa: 44;/* Segment-Frame Absolute Address */
+	unsigned long     : 3;
+	unsigned long av  : 1; /* ACCF-Validity Control */
+	unsigned long acc : 4; /* Access-Control Bits */
+	unsigned long f   : 1; /* Fetch-Protection Bit */
+	unsigned long fc  : 1; /* Format-Control */
+	unsigned long p   : 1; /* DAT-Protection Bit */
+	unsigned long iep : 1; /* Instruction-Execution-Protection */
+	unsigned long     : 2;
+	unsigned long i   : 1; /* Segment-Invalid Bit */
+	unsigned long cs  : 1; /* Common-Segment Bit */
+	unsigned long tt  : 2; /* Table-Type Bits */
+	unsigned long     : 2;
+};
+
+union segment_table_entry {
+	unsigned long val;
+	struct segment_table_entry_fc0 fc0;
+	struct segment_table_entry_fc1 fc1;
+	struct {
+		unsigned long   : 53;
+		unsigned long fc: 1; /* Format-Control */
+		unsigned long   : 4;
+		unsigned long i : 1; /* Segment-Invalid Bit */
+		unsigned long cs: 1; /* Common-Segment Bit */
+		unsigned long tt: 2; /* Table-Type Bits */
+		unsigned long   : 2;
+	};
+};
+
+union page_table_entry {
+	unsigned long val;
+	struct {
+		unsigned long pfra: 52;/* Page-Frame Real Address */
+		unsigned long z   : 1; /* Zero Bit */
+		unsigned long i   : 1; /* Page-Invalid Bit */
+		unsigned long p   : 1; /* DAT-Protection Bit */
+		unsigned long iep : 1; /* Instruction-Execution-Protection */
+		unsigned long     : 8;
+	};
+};
+
+enum {
+	TABLE_TYPE_SEGMENT = 0,
+	TABLE_TYPE_REGION3 = 1,
+	TABLE_TYPE_REGION2 = 2,
+	TABLE_TYPE_REGION1 = 3
+};
+
+#endif /* _S390_DAT_BITS_H */
diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index 5bf3d94e9dda..e65f597e3044 100644
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -14,167 +14,10 @@ 
 #include <asm/access-regs.h>
 #include <asm/fault.h>
 #include <asm/gmap.h>
+#include <asm/dat-bits.h>
 #include "kvm-s390.h"
 #include "gaccess.h"
 
-union asce {
-	unsigned long val;
-	struct {
-		unsigned long origin : 52; /* Region- or Segment-Table Origin */
-		unsigned long	 : 2;
-		unsigned long g  : 1; /* Subspace Group Control */
-		unsigned long p  : 1; /* Private Space Control */
-		unsigned long s  : 1; /* Storage-Alteration-Event Control */
-		unsigned long x  : 1; /* Space-Switch-Event Control */
-		unsigned long r  : 1; /* Real-Space Control */
-		unsigned long	 : 1;
-		unsigned long dt : 2; /* Designation-Type Control */
-		unsigned long tl : 2; /* Region- or Segment-Table Length */
-	};
-};
-
-enum {
-	ASCE_TYPE_SEGMENT = 0,
-	ASCE_TYPE_REGION3 = 1,
-	ASCE_TYPE_REGION2 = 2,
-	ASCE_TYPE_REGION1 = 3
-};
-
-union region1_table_entry {
-	unsigned long val;
-	struct {
-		unsigned long rto: 52;/* Region-Table Origin */
-		unsigned long	 : 2;
-		unsigned long p  : 1; /* DAT-Protection Bit */
-		unsigned long	 : 1;
-		unsigned long tf : 2; /* Region-Second-Table Offset */
-		unsigned long i  : 1; /* Region-Invalid Bit */
-		unsigned long	 : 1;
-		unsigned long tt : 2; /* Table-Type Bits */
-		unsigned long tl : 2; /* Region-Second-Table Length */
-	};
-};
-
-union region2_table_entry {
-	unsigned long val;
-	struct {
-		unsigned long rto: 52;/* Region-Table Origin */
-		unsigned long	 : 2;
-		unsigned long p  : 1; /* DAT-Protection Bit */
-		unsigned long	 : 1;
-		unsigned long tf : 2; /* Region-Third-Table Offset */
-		unsigned long i  : 1; /* Region-Invalid Bit */
-		unsigned long	 : 1;
-		unsigned long tt : 2; /* Table-Type Bits */
-		unsigned long tl : 2; /* Region-Third-Table Length */
-	};
-};
-
-struct region3_table_entry_fc0 {
-	unsigned long sto: 52;/* Segment-Table Origin */
-	unsigned long	 : 1;
-	unsigned long fc : 1; /* Format-Control */
-	unsigned long p  : 1; /* DAT-Protection Bit */
-	unsigned long	 : 1;
-	unsigned long tf : 2; /* Segment-Table Offset */
-	unsigned long i  : 1; /* Region-Invalid Bit */
-	unsigned long cr : 1; /* Common-Region Bit */
-	unsigned long tt : 2; /* Table-Type Bits */
-	unsigned long tl : 2; /* Segment-Table Length */
-};
-
-struct region3_table_entry_fc1 {
-	unsigned long rfaa : 33; /* Region-Frame Absolute Address */
-	unsigned long	 : 14;
-	unsigned long av : 1; /* ACCF-Validity Control */
-	unsigned long acc: 4; /* Access-Control Bits */
-	unsigned long f  : 1; /* Fetch-Protection Bit */
-	unsigned long fc : 1; /* Format-Control */
-	unsigned long p  : 1; /* DAT-Protection Bit */
-	unsigned long iep: 1; /* Instruction-Execution-Protection */
-	unsigned long	 : 2;
-	unsigned long i  : 1; /* Region-Invalid Bit */
-	unsigned long cr : 1; /* Common-Region Bit */
-	unsigned long tt : 2; /* Table-Type Bits */
-	unsigned long	 : 2;
-};
-
-union region3_table_entry {
-	unsigned long val;
-	struct region3_table_entry_fc0 fc0;
-	struct region3_table_entry_fc1 fc1;
-	struct {
-		unsigned long	 : 53;
-		unsigned long fc : 1; /* Format-Control */
-		unsigned long	 : 4;
-		unsigned long i  : 1; /* Region-Invalid Bit */
-		unsigned long cr : 1; /* Common-Region Bit */
-		unsigned long tt : 2; /* Table-Type Bits */
-		unsigned long	 : 2;
-	};
-};
-
-struct segment_entry_fc0 {
-	unsigned long pto: 53;/* Page-Table Origin */
-	unsigned long fc : 1; /* Format-Control */
-	unsigned long p  : 1; /* DAT-Protection Bit */
-	unsigned long	 : 3;
-	unsigned long i  : 1; /* Segment-Invalid Bit */
-	unsigned long cs : 1; /* Common-Segment Bit */
-	unsigned long tt : 2; /* Table-Type Bits */
-	unsigned long	 : 2;
-};
-
-struct segment_entry_fc1 {
-	unsigned long sfaa : 44; /* Segment-Frame Absolute Address */
-	unsigned long	 : 3;
-	unsigned long av : 1; /* ACCF-Validity Control */
-	unsigned long acc: 4; /* Access-Control Bits */
-	unsigned long f  : 1; /* Fetch-Protection Bit */
-	unsigned long fc : 1; /* Format-Control */
-	unsigned long p  : 1; /* DAT-Protection Bit */
-	unsigned long iep: 1; /* Instruction-Execution-Protection */
-	unsigned long	 : 2;
-	unsigned long i  : 1; /* Segment-Invalid Bit */
-	unsigned long cs : 1; /* Common-Segment Bit */
-	unsigned long tt : 2; /* Table-Type Bits */
-	unsigned long	 : 2;
-};
-
-union segment_table_entry {
-	unsigned long val;
-	struct segment_entry_fc0 fc0;
-	struct segment_entry_fc1 fc1;
-	struct {
-		unsigned long	 : 53;
-		unsigned long fc : 1; /* Format-Control */
-		unsigned long	 : 4;
-		unsigned long i  : 1; /* Segment-Invalid Bit */
-		unsigned long cs : 1; /* Common-Segment Bit */
-		unsigned long tt : 2; /* Table-Type Bits */
-		unsigned long	 : 2;
-	};
-};
-
-enum {
-	TABLE_TYPE_SEGMENT = 0,
-	TABLE_TYPE_REGION3 = 1,
-	TABLE_TYPE_REGION2 = 2,
-	TABLE_TYPE_REGION1 = 3
-};
-
-union page_table_entry {
-	unsigned long val;
-	struct {
-		unsigned long pfra : 52; /* Page-Frame Real Address */
-		unsigned long z  : 1; /* Zero Bit */
-		unsigned long i  : 1; /* Page-Invalid Bit */
-		unsigned long p  : 1; /* DAT-Protection Bit */
-		unsigned long iep: 1; /* Instruction-Execution-Protection */
-		unsigned long	 : 8;
-	};
-};
-
 /*
  * vaddress union in order to easily decode a virtual address into its
  * region first index, region second index etc. parts.
@@ -632,7 +475,7 @@  static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
 	iep = ctlreg0.iep && test_kvm_facility(vcpu->kvm, 130);
 	if (asce.r)
 		goto real_address;
-	ptr = asce.origin * PAGE_SIZE;
+	ptr = asce.rsto * PAGE_SIZE;
 	switch (asce.dt) {
 	case ASCE_TYPE_REGION1:
 		if (vaddr.rfx01 > asce.tl)
@@ -1379,7 +1222,7 @@  static int kvm_s390_shadow_tables(struct gmap *sg, unsigned long saddr,
 	parent = sg->parent;
 	vaddr.addr = saddr;
 	asce.val = sg->orig_asce;
-	ptr = asce.origin * PAGE_SIZE;
+	ptr = asce.rsto * PAGE_SIZE;
 	if (asce.r) {
 		*fake = 1;
 		ptr = 0;